Method for producing acrylamide from acrylonitrile

ABSTRACT

Dilute aqueous solutions of acrylonitrile, the pH of which is adjusted to 10-14, may be electrolyzed using A.C. current and copper electrodes to produce acrylamide.

United States Patent [1 1 Epple 1 v METHOD FOR PRODUCING ACRYLAMIDE FROM ACRYLONITRILE [75] inventor: Donald G. Epple, Oaklziiim, I11.

[73] Assignee: Nalco Chemical Company, Chicago,

22 Filed: June9, 1972 211 App1.No,:263,745'

[52] US. Cl 204/74, 204/73 R, 204/73 A,

3,193,478 7/1965 Baizer 204/73 A Aug. 28, 1973 3,381,034 4/1968 Greene et a1. 260/557 R 3,616,320 10/1971 Beck et a1 204/73 A' 3,631,104 12/1971 Habermann et a1. 260/561 N Primary Examiner-E. C. Edmundson Attorney-John G. Premo et a1.

[57] ABSTRACT Dilute aqueous solutions of acrylonitrile, thepH of which is adjusted to 10-14, may be electrolyzed using A.C. current and copper electrodes to produce acrylamide.

2 Claims, No Drawings METHOD FOR PRODUCING ACRYLAMIDE FROM ACRYLONITRILE Several methods are now known for producing acrylamide based on the hydrolysis of acrylonitrile. One such method-is the acid hydrolysis of acrylonitrileThis method is not too desirable from a manufacturer's standpoint since inorganic salts are produced as a by- .product, which salts are difficult'to dispose of in an economical and pollution-free manner.

Another method for converting acrylonitrile to acrylamide resides in the catalytic hydrolysis of acrylonitrile in water, using a variety of catalysts such as, for instance, the oxides or reduced oxides of copper, zinc, silver, as well as these compounds supported ona carrier. While this hydrolytic. approach has certain advantages, it still necessitatesthat the catalyst be separated from the finished product. Also, the cost of these catalysts both with respect to the materials used to prepare the catalyst as well as the minipulative steps required, to treat the catalyst to convert it to an active species I add to the costs and disadvantages of the process.

; If it were possible to provide asimple, substantially pollution-free method for rapidly and economically converting acrylonitrile to acrylamide, an advantage to the art would be afforded. a

INVENTION accordance withthe invention, 'it hasbeen found that dilute'aqueous solutions of acrylonitrile may be ef- I quency of which may be as low as one cycle per. sec.

although in most instances the electrical reaction gen-' crates heat. When heat is employed, it should be controlled so that the reaction'temperature does not exceed theboilin'g point of either the water of acrylonitrile'. The acrylonitrile solutions may contain from about 1 percent to about 10 percent by weight of the ficiently hydrolyzed electrolytically using copperelectrodes and an A.C. current to produce acrylamide. An important aspect of the invention is the pH of the acrylonitrile solution during its electrolysis. The pH is generally within therange of 1014. Most preferably, it is within'the pI-I rangevof 9.5-13.5.

, pH ADJUSTMENT I The pH of the acrylonitrilesolution may be adjusted by using an inorganic basic compound or basic organic nitrogen compound, the basisity of which is sufficient to impart to the solution of pH within the ranges ennumerated above.

For instance, good results have been achieved by using sodium hydroxide, sodium carbonate or mixtures thereof. Good results are also achieved when the reac tion is run using as the pH adjustment chemical, a

' strong water soluble amine or quaternary ammonium hydroxide or salt.

The pH, as indicated, is critical in allowing the hydrolysis of the nitrile solution to proceed rapidly using minimum amounts of current.

CONDITIONS OF'THE ELECTROLY SIS In conducting the electrolysis, conventional electro-' lytical apparatus maybe employed. The electrodes, as indicated,'are formed from copper which may be in the shape of rods, bars, screens and the like. In certain types of electrolytic cells, the electrolysis vessel may be formed of copper, and be utilized as an electrode. Similarly, copper shot or powder contained in a suitable p0.- rous container may be employed as an electrode.

The alternating current may have a frequency range between 60-120 cycles per. sec.,, although in certain instances the'frequency maybe as high as 500 cycles per. see. In addition to using altemating current as such, square'wave D. C. current may be used, the freacrylonitrile.

. EXAMPLE I To illustrate the invention, the following are presented by way of Example. In all cases, unless stated otherwise, the acrylonitrile I solutions electrolyzed, contained 7 percent by weight. All of the experiments used standard laboratory electrolytic cells.

CONDITIONS A.C. line voltage was lowered to 15/20 of its value by means of a transformer. The pH of a 4 percent solution, of acrylonitrile was adjusted to 13.5 with a mixtureof sodium carbonate & sodium hydroxide. 7

RESULTS I Time I Acrylamide 1 min.- 0.006 5 min. 0.006 15 min. 0.01 1 hour 0.07 1.5 hour 0.06'

EXAMPLE II The sametest procedure as in Exmple 1 except that square wave DC 1 cycle per second at 0.5 amps was used. Tetramethyl ammonium hydroxide was used in place of NaOH Na,CO,. The results are presented below:

Time & Acrylamide (wt/vol.) ACN wt./vol. 2/22/ B (Blank) 0.02% 2.7%

1 (2 hrs.) 0.60% 2.0% 2 (4 hrs.) 0.50% 1.3% 3 (24 hrs.) 0.20% 1.4% a

justed with an electrolyte to between 9.5-14, continu-' ing said electrolysis until a portion of the acrylonitrile has been converted to acrylamide and then separating and recovering the acrylamide.

2. The method of claim 1 where the pH is within the range of 10- 14.

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2. The method of claim 1 where the pH is within the range of 10-14. 